SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8039b36519466b43d3c296e52e48e7dab0f12df81cb4f13f2f2f64a878a5f2db' 
  AND token = 'bRjyyhgtx5ZA+6Pr4Vv38HzgC/AvcOxFlKkkYxpQNS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}